Deposition Of Ceramic Particles Research Articles

Effect of applying electric field on suspension stability during electrophoretic deposition of ceramic particles in nonaqueous media: a case study

Effect of applying electric field on suspension stability during electrophoretic deposition of ceramic particles in nonaqueous media: a case study

Mechanical properties of TiO2 coatings deposited by low pressure cold spraying

Titanium dioxide is a very popular ceramic material due to its outstanding properties, e.g. photocatalytic conversion. Titania coatings are able to activate chemical reactions on its surface. However, photocatalytic activity strongly depends on crystal structure, the size and shape of crystallites and also the surface area. This article is devoted to the mechanical tests of TiO2 coatings obtained by the Cold Spray method considered as a promising alternative to conventional techniques, such as Flame or Plasma Spray. However, the degree of the method development with regards to ceramic coatings is still low. It should be noted that the latest scientific trends show progress in the deposition of ceramic particles via cold spray. The crucial problem in obtaining thick coating seems to be the lack of ceramic deformation combined with high differences in the coefficient of thermal expansion between a ceramic coating and a metal substrate. To solve this problem, an amorphous phase known as soft-ceramic can be used. The high value of kinetic energy ensures phase transition into anatase during cold spraying. In the presented study, the mechanical properties of titanium dioxide coatings deposited by low pressure cold spraying onto aluminium and steel substrates were investigated and compared. The powders of the amorphous phase, anatase and rutile provide different coatings and thus various types of research were performed to analyse the mechanical properties of the coatings, e.g. scratch test, nanoindentation, coatings microhardness, together with SEM analysis. An amorphous coating, free from delamination and microcracks, showed the highest adhesion with a critical load of 15.8 ± 1.3 N. All the coatings deposited onto the steel substrate showed higher hardness. Rutile formed sintered agglomerates with local hardness up to 1292 ± 357 HV0.01 and the coating mean elastic modulus of 29.8 GPa.

Effect of Heat Treatment & Machining Process for Deposition of Al2O3 Nano Particles on Steel

Industries use various methods for deposition of nano particles on metals. Nano particles of different sizes are used to improve the surface properties. Especially deposition of ceramic particles on metals is very essential to improve the surface characteristics. In this paper we focused on deposition of Al2O3 nano particles on steel by machining process and heat treatment process.A considerable difference in hardness is achieved after deposition. The coating thickness is caused due to temperatures generated at the time of machining and molecular bonding between aluminium oxide and mild steel. Surface roughness is lowered after deposition. Temperatures are lowered after machining process due to deposition of aluminium oxide nano particles hence it can be as coolant and lubricant to some extent. Microstructures show finer molecular structure after coating. Corrosion resistance is improved as it is observed by naked eye.

The erosion performance of particle reinforced metal matrix composite coatings produced by co-deposition cold gas dynamic spraying

This work reports on the erosion performance of three particle reinforced metal matrix composite coatings, co-deposited with an aluminium binder via cold-gas dynamic spraying. The deposition of ceramic particles is difficult to achieve with typical cold spray techniques due to the absence of particle deformation. This issue has been overcome in the present study by simultaneously spraying the reinforcing particles with a ductile metallic binder which has led to an increased level of ceramic/cermet particles deposited on the substrate with thick (>400μm) coatings produced. The aim of this investigation was to evaluate the erosion performance of the co-deposited coatings within a slurry environment. The study also incorporated standard metallographic characterisation techniques to evaluate the distribution of reinforcing particles within the aluminium matrix. All coatings exhibited poorer erosion performance than the uncoated material, both in terms of volume loss and mass loss. The Al2O3 reinforced coating sustained the greatest amount of damage following exposure to the slurry and recorded the greatest volume loss (approx. 2.8mm3) out of all of the examined coatings. Despite the poor erosion performance, the WC-CoCr reinforced coating demonstrated a considerable hardness increase over the as-received AA5083 (approx. 400%) and also exhibited the smallest free space length between adjacent particles. The findings of this study reveal that the removal of the AA5083 matrix by the impinging silicon carbide particles acts as the primary wear mechanism leading to the degradation of the coating. Analysis of the wear scar has demonstrated that the damage to the soft matrix alloy takes the form of ploughing and scoring which subsequently exposes carbide/oxide particles to the impinging slurry.

AN ENGINEERING MODEL FOR SOLID-LIQUID PHASE CHANGE WITHIN SPRAYED CERAMIC COATINGS OF NONUNIFORM THICKNESS

The heat transfer within coatings and substrate materials during plasma deposition of ceramic particles has been modeled numerically using an enthalpy-based finite volume method. The particle distribution within the spray is described by a Gaussian function, while the effects of heat transfer to the substrate from the plasma torch are included using empirical correlations. Using the model, the temperature evolution in the substrate as well as in the coating is predicted in a parametric study involving the plasma torch traversing velocity, the thermal contact resistance between splats, the material deposition rate, as well as the substrate cooling mechanism and plasma jet characteristics. The possibility of melting and subsequent resolidification of material in the substrate as well as in the coating under certain conditions is illustrated.